Various technical solutions are used for sounding a string of stringed instrument in apparatuses for playing musical pieces automatically.
Thus, the Great Britain Patent 1426203 (publ. on Feb. 25, 1976) describes an apparatus where each string is engaged for sounding with its own gear wheel having teeth at a side surface, which gear wheel being driven and, correspondingly, engaged with the string when pressing the string due to bearing against a spring-loaded lever arm supporting this wheel near the string. This solution, besides its complexity, cannot ensure qualitative string sounding because of fact that the string, after being engaged with one tooth, can contact with the next tooth, wherefore the sound could be rattling or muffled.
The U.S. Pat. No. 6,723,904 (publ. on Apr. 20, 2004) describes an apparatus for sounding a string of stringed instrument which uses also a rotating wheel having four teeth and an axle parallel to the string. On actuating a solenoid drawing that axle, the wheel rotates following the foreseen guides and engaging the string. A disadvantage of such solution consists in its complexity.